13747361domain: NAppears in sequencesa(n) is the smallest Fermat pseudoprime to base 2 such that gpf(p-1) = prime(n) for all prime factors p of a(n).at n=27A327789Fermat pseudoprimes to base 2 (A001567) k such that A003961(k) is also a Fermat pseudoprime to base 2.at n=5A346568